CN114773613B - Preparation method and application of high-performance modified nano silicon dioxide - Google Patents
Preparation method and application of high-performance modified nano silicon dioxide Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G83/00—Macromolecular compounds not provided for in groups C08G2/00 - C08G81/00
- C08G83/001—Macromolecular compounds containing organic and inorganic sequences, e.g. organic polymers grafted onto silica
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
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Abstract
The invention discloses a preparation method and application of high-performance modified nano silicon dioxide, wherein the method comprises the following steps: step 1, coupling nano silicon dioxide to obtain coupled nano silicon dioxide; step 2, modifying the coupled nano silicon dioxide by adopting methyl acrylate and alkylamine/alcohol to obtain modified nano silicon dioxide; and step 3, grafting the modified nano silicon dioxide with polyethylene glycol monomethyl ether acrylate through Michael addition reaction to obtain polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide, wherein the polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide can be used for replacing cement with building materials. The invention has simple process, wide sources of raw materials and great application prospect.
Description
Technical Field
The invention relates to the field of preparation methods of modified nano silicon dioxide, in particular to a preparation method and application of high-performance modified nano silicon dioxide.
Background
With the rapid development of concrete technology, there are increasing demands on high-performance concrete, such as high strength, high durability, good workability, etc. The doped nano material, such as nano silicon dioxide, can improve the strength of the concrete, improve the microstructure of the concrete, increase the compaction degree and further improve the durability of the concrete. However, nano silicon dioxide has large specific surface area and high surface energy, and is easy to agglomerate in the mixing process of cement, so that the water demand is increased, and the working performance of the cement-based material is reduced. In order to solve the agglomeration problem of nano silicon dioxide in concrete, water-soluble polymer polyethylene glycol monomethyl ether acrylate can be grafted on the surface of silicon dioxide, and then cement is partially replaced to be used as a cementing material, so that the compatibility of the nano silicon dioxide and a cement-based material is improved, and the application prospect of the nano silicon dioxide in the cement-based composite material is further improved.
Disclosure of Invention
The invention aims to provide a preparation method and application of high-performance modified nano silicon dioxide, which are used for solving the problem of agglomeration existing in the prior art when the nano silicon dioxide is used in concrete.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the preparation method of the high-performance modified nano silicon dioxide comprises the following steps:
step 1, performing functionalization treatment on nano silicon dioxide by adopting a coupling agent A to obtain coupled nano silicon dioxide;
step 2, chain extension is carried out on the surface of the nano silicon dioxide coupled in the step 1 by adopting methyl acrylate and alkylamine/alcohol to obtain the nano silicon dioxide modified by the methyl acrylate and the alkylamine/alcohol, wherein the alkylamine/alcohol is HO (CH 2 ) n OH、C n H 2n+2 O 3 、H 2 N(CH 2 )nNH 2 、C n H 2n+4 N 3 One or a combination of any two or more of the above, wherein n=2 to 12;
and step 3, grafting the modified nano silicon dioxide obtained in the step 2 with polyethylene glycol monomethyl ether acrylate through Michael addition reaction to obtain a final product polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide.
Further, the procedure of step 1 is as follows:
firstly, drying nano silicon dioxide in a vacuum environment at 50-110 ℃ for 10-24h; dispersing the dried nano silicon dioxide and the coupling agent A in toluene, performing ultrasonic dispersion for 15-60min, and then stirring at 60-120 ℃ for reaction for 8-24h; after the reaction is finished, the coupled nano silicon dioxide is obtained through centrifugal separation, washing, filtering and drying.
In the step 1, the mass ratio of the nano silicon dioxide to the coupling agent A to the toluene is 1-5: 2-10: 3 to 40.
Further, the procedure of step 2 is as follows:
adding the coupled nano silicon dioxide and methyl acrylate obtained in the step 1 into solvent methanol, and stirring and reacting for 10-48 hours at 30-80 ℃; then adding 1-10mL of alkylamine/alcohol and stirring for reaction for 10-24 hours; cooling to room temperature after the reaction is finished, and obtaining the methyl acrylate and alkylamine/alcohol modified nano silicon dioxide after centrifugal separation, washing and vacuum drying.
In the step 2, the mass ratio of the nano silicon dioxide to the methyl acrylate to the alkylamine/alcohol to the solvent methanol is as follows: 2 to 50: 1-20: 1-20: 10 to 100 percent.
Further, the procedure of step 3 is as follows:
adding the modified nano silicon dioxide obtained in the step 2 into dimethyl sulfoxide solvent, then adding polyethylene glycol monomethyl ether acrylate, and stirring at 30-80 ℃ for reaction for 24-72 hours; after the reaction is finished, the polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide serving as a final product is obtained through centrifugal separation, washing and vacuum drying.
In the step 3, the mass ratio of the modified nano silicon dioxide, polyethylene glycol monomethyl ether acrylate and solvent dimethyl sulfoxide is as follows: 1-10:5-20: 10 to 100.
The application of the high-performance modified nano silicon dioxide is used for replacing the equivalent cement to be doped into a concrete system so as to improve the mechanical property of a cement-based composite material and solve the problems of poor compatibility, low strength and high construction difficulty caused by directly doping the nano silicon dioxide.
The invention can greatly improve the fluidity of the cement-based material by only adding a small amount of nano silicon dioxide (about 0.25% -1% of the mass of silicate cement), and can remarkably improve the mechanical property of concrete.
The high-performance modified nano silicon dioxide used for building materials is polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide, and the chemical formula is as follows:
the invention aims to provide a preparation method and application of high-performance modified nano silicon dioxide, and a high-hydrophilicity polymer acrylic polyester monomer is grafted on the surface of the nano silicon dioxide through a simple process means. In addition, a large amount of water reducing agent monomers are grafted on the surface of the modified nano silicon dioxide, so that the problem of compatibility with cement-based materials is greatly improved, the problems of agglomeration in cement materials, high water demand and the like caused by large specific surface area of the silicon dioxide are solved, and the problems of local brittle fracture and the like caused by agglomeration of the silicon dioxide in the cement-based materials are avoided. Meanwhile, the nano-inorganic powder has a large number of water-soluble groups, so that the dispersion is good, and the problem of agglomeration of the nano-inorganic powder can be well solved.
According to the invention, polyethylene glycol monomethylmethacrylate is grafted on the surface of nano silicon dioxide, so that the brittleness of the cement composite machine material can be reduced, the toughness of the cement composite machine material can be increased, the water consumption and the cement consumption can be reduced, the compressive strength of concrete can be obviously improved, and the requirement of high-performance cement-based composite materials on the compressive strength can be completely met. The preparation method has the advantages of low reaction temperature, mild condition, simple post-treatment and low industrialization cost.
Drawings
FIG. 1 is an SEM image of nanosilica before modification.
Fig. 2 is an SEM image of the modified nanosilica.
FIG. 3 is an infrared contrast spectrum of the product of each step in the preparation process of the modified nano-silica.
FIG. 4 is a diagram of modified stone dust TG.
FIG. 5 is a graph of initial paste fluidity for a nano-silica doped cement
FIG. 6 is a 1h paste fluidity graph of a nanosilica doped cement
FIG. 7 is a graph of mortar fluidity for nano-silica doped sand
FIG. 8 is a slump plot of nano-silica doped concrete
FIG. 9 is 7d compressive strength of nano silica doped concrete
FIG. 10 is a graph of 28d compressive strength of nano silica doped concrete
Detailed Description
The invention will be further described with reference to the drawings and examples.
The coupling agent A modified nano silicon dioxide and polyethylene glycol monomethyl ether acrylate grafted modified nano silicon dioxide are prepared by the following steps:
step 1, firstly, drying nano silicon dioxide in a vacuum environment at 50-110 ℃ for 10-24 hours; dispersing the dried nano silicon dioxide and the coupling agent A in toluene, performing ultrasonic dispersion for 15-60min, and then stirring at 60-120 ℃ for reaction for 8-24h; after the reaction is finished, the coupled nano silicon dioxide is obtained through centrifugal separation, washing, filtering and drying.
In the step 1, the mass ratio of the nano silicon dioxide to the coupling agent A to the toluene is 1-5: 2-10: 3 to 40.
Step 2, adding the coupled nano silicon dioxide and methyl acrylate obtained in the step 1 into solvent methanol, and stirring and reacting for 10-48 hours at 30-80 ℃; then adding 1-10mL of alkylamine/alcohol and stirring for reaction for 10-24 hours; cooling to room temperature after the reaction is finished, and obtaining the methyl acrylate and alkylamine/alcohol modified nano silicon dioxide after centrifugal separation, washing and vacuum drying.
In the step 2, the mass ratio of the nano silicon dioxide to the methyl acrylate to the alkylamine/alcohol to the solvent methanol is as follows: 2 to 50: 1-20: 1-20: 10 to 100 percent.
Step 3, adding the modified nano silicon dioxide obtained in the step 2 into dimethyl sulfoxide solvent, then adding polyethylene glycol monomethyl ether acrylate, and stirring at 60-100 ℃ for reaction for 24-72 hours; after the reaction is finished, the polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide serving as a final product is obtained through centrifugal separation, washing and vacuum drying.
In the step 3, the mass ratio of the modified nano silicon dioxide, polyethylene glycol monomethyl ether acrylate and solvent dimethyl sulfoxide is as follows: 1-10:5-20: 10 to 100.
The final product of the invention is polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide, and the chemical formula is:
it can be used to replace cement for incorporation into concrete systems.
As shown in fig. 1 and 2, fig. 1 is an SEM of unmodified nano-silica, and fig. 2 is an SEM of modified nano-silica. It can be seen from fig. 1 that the unmodified nano silica has obvious agglomeration, while fig. 2 that the modified nano silica has obviously weakened agglomeration, which illustrates that the agglomeration of silica is effectively solved after a series of surface grafting.
As shown in fig. 3, fig. 3 is an infrared contrast spectrum of the product of each step in the preparation process of the modified nano-silica. In the figure, a curve a is a coupling agent A modified nano silicon dioxide infrared spectrum, a curve b is a nano silicon dioxide spectrum after methyl acrylate and alkylamine/alcohol treatment, and a curve c is a polyethylene glycol monomethyl ether acrylate grafted nano silicon dioxide infrared spectrum.
As can be seen from curve a of FIG. 3, at 1650cm -1 Is a bending vibration peak of amino group, 2865cm -1 The nearby C-H stretching vibration peaks are characteristic absorption peaks of the coupling agent A, which indicates that the coupling agent A is successfully grafted to the surface of the nano silicon dioxide. Curve b of fig. 3 is an infrared spectrum of methyl acrylate, alkylamine/alcohol modified nano silica, wherein compared to curve a of fig. 3, at 1455cm -1 、1650cm -1 Characteristic peaks appearing at the positions are CH respectively 2 And NH 2 In addition, at 2865cm -1 The peaks at the sites become more dense, indicating that the chain extension of the nanosilica by methyl acrylate, alkylamine/alcohol was successful. Curve c of FIG. 3 is the FTIR spectrum of polyethylene glycol Shan Jia acrylate-modified stone dust, 1455cm of which -1 Nearby CH 2 The stretching vibration peak is obviously increased and is 1650cm -1 NH at 2 It can be inferred that polyethylene glycol monomethacrylate has been successfully grafted onto the nanosilica surface by a significant decrease in the flexural vibration peak.
As shown in fig. 4, fig. 4 is a diagram of modified stone dust TG. In the figure, a curve a is a thermal weight spectrum of the coupling agent A modified nano silicon dioxide, a curve b is a thermal weight spectrum of the nano silicon dioxide after methyl acrylate and alkylamine/alcohol treatment, and a curve c is a thermal weight spectrum of the polyethylene glycol monomethacrylate grafted nano silicon dioxide. As can be seen from the curve a of FIG. 4, the grafting rate of the coupling agent A on the surface of the nano silicon dioxide is about 5%, the grafting rate of methyl acrylate and alkylamine/alcohol on the nano silicon dioxide surface is about 10% as can be seen from the curve b of FIG. 4, and the grafting rate of polyethylene glycol monomethacrylate on the surface of the nano silicon dioxide is about 3% as can be seen from the curve c of FIG. 4. Thermogravimetric data further demonstrates the successful performance of the silica surface grafting reaction.
Example 1:
1. the nano silicon dioxide is put into a vacuum drying oven to be dried for 24 hours at 100 ℃ before being used.
2. Adding 6g of dried nano silicon dioxide and 60mL of toluene into a 100mL three-neck flask, carrying out ultrasonic treatment for 15min, then adding a silane coupling agent A, placing the three-neck flask into a magnetic stirring device, then adjusting a reactor to react under an oil bath at 100 ℃, cooling to room temperature after reacting for 24h, centrifuging the obtained suspension by using a centrifuge, dissolving the solid obtained by centrifugation in toluene again, centrifuging again, separating out, carrying out vacuum filtration under reduced pressure, and carrying out vacuum drying on the product at 50 ℃ for 24h to obtain the coupling agent modified nano silicon dioxide.
3. 6g of coupling agent modified nano silicon dioxide and 120mL of methanol are put into a 250mL three-neck flask, 3mL of methyl acrylate is added under magnetic stirring, the reactor is regulated to react for 24 hours at 50 ℃ under an oil bath, then 4.5mL of alkylamine/alcohol is added, stirring is continued for 24 hours, after the reaction is finished, the mixture is cooled to room temperature, the obtained suspension is centrifugally separated by a centrifugal machine, washed by the methanol, then the mixture is subjected to vacuum filtration, and the product is dried under vacuum for 24 hours at 50 ℃ to obtain the methyl acrylate and alkylamine/alcohol modified nano silicon dioxide.
4. Adding 6g of methyl acrylate, alkylamine/alcohol treated nano silicon dioxide and 100mL of dimethyl sulfoxide into a 250mL three-neck flask, adding 25mL of polyethylene glycol monomethyl ether acrylate under stirring, regulating the temperature of a reactor to react for 72h in an oil bath at 75 ℃, cooling to room temperature after the reaction is finished, centrifugally separating the obtained suspension by using a centrifugal machine, washing by using methanol, carrying out vacuum filtration, and carrying out vacuum drying on the product at 50 ℃ for 24h to obtain polyethylene glycol monomethyl ether acrylate grafted nano silicon dioxide.
Example 2:
1. the nano silicon dioxide is put into a vacuum drying oven to be dried for 24 hours at 110 ℃ before being used.
2. Adding 12g of dried nano silicon dioxide and 120mL of toluene into a 250mL three-neck flask, carrying out ultrasonic treatment for 15min, then adding a silane coupling agent A, placing the three-neck flask into a magnetic stirring device, then adjusting a reactor to react under an oil bath at 100 ℃, cooling to room temperature after reacting for 24h, centrifuging the obtained suspension by using a centrifuge, dissolving the solid obtained by centrifugation in toluene again, centrifuging again, separating out, carrying out vacuum filtration under reduced pressure, and carrying out vacuum drying on the product at 50 ℃ for 24h to obtain the coupling agent modified nano silicon dioxide.
3. Loading 12g of coupling agent modified nano silicon dioxide and 240mL of methanol into a 500mL three-neck flask, adding 12mL of methyl acrylate under magnetic stirring, regulating a reactor to react for 24h at 50 ℃ under an oil bath, then adding 9mL of alkylamine/alcohol, continuously stirring for 24h, cooling to room temperature after the reaction is finished, centrifuging the obtained suspension by using a centrifuge, washing by using methanol, carrying out vacuum filtration, and drying the product under vacuum at 50 ℃ for 24h to obtain the methyl acrylate and alkylamine/alcohol modified nano silicon dioxide.
4. Adding 12g of methyl acrylate, alkylamine/alcohol treated nano silicon dioxide and 200mL of dimethyl sulfoxide into a 500mL three-neck flask, adding 50mL of polyethylene glycol monomethyl ether acrylate under stirring, regulating the temperature of a reactor to react for 72h in an oil bath at 75 ℃, cooling to room temperature after the reaction is finished, centrifugally separating the obtained suspension by using a centrifugal machine, washing by using methanol, carrying out vacuum filtration, and carrying out vacuum drying on the product at 50 ℃ for 24h to obtain polyethylene glycol monomethyl ether acrylate grafted nano silicon dioxide.
Example 3: 1. the nano silicon dioxide is put into a vacuum drying oven to be dried for 24 hours at 110 ℃ before being used.
2. Adding 18g of dried nano silicon dioxide and 180mL of toluene into a 250mL three-neck flask, carrying out ultrasonic treatment for 15min, then adding a silane coupling agent A, placing the three-neck flask into a magnetic stirring device, then adjusting a reactor to react under an oil bath at 100 ℃, cooling to room temperature after reacting for 24h, centrifuging the obtained suspension by using a centrifuge, dissolving the solid obtained by centrifugation in toluene again, centrifuging again, separating out, carrying out vacuum filtration under reduced pressure, and drying the product under vacuum at 50 ℃ for 24h to obtain the coupling agent modified nano silicon dioxide.
3. 18g of coupling agent modified nano silicon dioxide and 360mL of methanol are put into a 250mL three-neck flask, 6mL of methyl acrylate is added under magnetic stirring, the reactor is regulated to react for 24 hours at 50 ℃ under an oil bath, then 20mL of alkylamine/alcohol is added, stirring is continued for 24 hours, after the reaction is finished, the mixture is cooled to room temperature, the obtained suspension is centrifugally separated by a centrifugal machine, washed by the methanol, then vacuum filtration is carried out, and the product is dried under vacuum for 24 hours at 50 ℃ to obtain the methyl acrylate and alkylamine/alcohol modified nano silicon dioxide.
4. Adding 18g of methyl acrylate, alkylamine/alcohol treated nano silicon dioxide and 300mL of dimethyl sulfoxide into a 500mL three-neck flask, adding 80mL of polyethylene glycol monomethyl ether acrylate under stirring, regulating the temperature of a reactor to react for 72h in an oil bath at 75 ℃, cooling to room temperature after the reaction is finished, centrifugally separating the obtained suspension by using a centrifugal machine, washing by using methanol, carrying out vacuum filtration, and vacuum drying the product at 50 ℃ for 24h to obtain polyethylene glycol monomethyl ether acrylate grafted nano silicon dioxide.
The polyethylene glycol monomethyl ether acrylate grafted nano silicon dioxide prepared by the invention is used for replacing cement by equal mass, a polycarboxylate water reducer is used for carrying out a paste fluidity experiment, and the result of the paste fluidity performance test is shown in table l. Table 1 is as follows:
TABLE 1 Cement paste fluidity of modified nanosilica in different amounts to replace equal mass cement and polycarboxylic acid water reducer
In order to detect the adaptability of the modified nano silicon dioxide to cement and a polycarboxylate water reducer, experiments are carried out by referring to a clean slurry fluidity test method in GB8077-2000 concrete admixture homogeneity test method. The adaptability of the modified nano silicon dioxide to cement and the polycarboxylate water reducer is studied by adjusting the mixing amount of the modified nano silicon dioxide (the mass fraction of the nano silicon dioxide to the experimental standard cement). The cement adopts standard cement specified in GB8076-2008 concrete admixture, the mixing water is tap water, the water reducer is a polycarboxylic acid high-performance water reducer, the mixing amount of the water reducer is 1% of the mass of the standard cement, and the water cement ratio is 0.29.
As can be seen from table 1, the unmodified nano silica is incorporated into the cement paste, the fluidity of the paste is gradually reduced with the increase of the amount of the nano silica incorporated therein, and the fluidity retention is also gradually reduced with the increase of the amount of the nano silica incorporated therein, because the nano silica has a large specific surface area and a high specific surface energy, is easily agglomerated in the cement paste, and consumes the water consumption greatly. The modified nano-silica is incorporated into the cement paste fluid, the initial paste fluidity is not affected by the addition of the modified nano-silica, and the paste fluidity after 1h is significantly increased compared with that of the unmodified nano-silica. The modified nano silicon dioxide surface is grafted with a large amount of hydrophilic groups polyethylene glycol monomethyl ether acrylate, so that the specific surface area of the nano silicon dioxide is effectively reduced, and meanwhile, the polyethylene glycol monomethyl ether acrylate has larger steric hindrance, so that the paste fluidity of cement can be increased to a certain extent, and the agglomeration of the nano silicon dioxide is obviously improved.
In order to detect the adaptability of the modified nano silicon dioxide and the cement mortar, the experiment is carried out by referring to the mortar fluidity test method in GB8077-2000 concrete admixture homogeneity test method, and the machine-made sand is adopted in the experiment to compare the adaptability of the nano silicon dioxide and the modified nano silicon dioxide to the cement mortar because the river sand is forbidden to be mined at present. The adaptability of the modified nano silicon dioxide and cement mortar is studied by adjusting the mass fraction of the modified nano silicon dioxide (the nano silicon dioxide accounts for the experimental standard cement). The cement was a standard cement specified in the standard of GB8076-2008 concrete admixture, and the mixed water was tap water, as shown in Table 2, table 2 below:
table 2 experiment for adaptability of polyethylene glycol monomethylmethacrylate modified stone dust cement mortar
As can be seen from table 2, when the unmodified nano silica is incorporated into the cement mortar fluid, the mortar fluidity is significantly reduced with the addition of the nano silica, mainly because the nano silica is easy to agglomerate and adsorbs a large amount of water, so that the mortar fluidity is significantly reduced. The modified nano silicon dioxide is doped into mortar fluid, the mortar fluidity is not obviously reduced, and compared with the unmodified nano silicon dioxide, the mortar fluidity is obviously increased, which indicates that the grafted polyethylene glycol monomethyl ether acrylate can effectively increase the compatibility of the nano silicon dioxide and cement-based materials.
In order to study the influence of the modified nano silicon dioxide on the compressive strength of the concrete, the experiment is evaluated according to GB/T50107-2020 concrete strength test evaluation Standard. The relation between slump and compressive strength of the nano silicon dioxide and concrete is studied by adjusting the mixing amount of the nano silicon dioxide to be 0.25%, 0.5% and 1% of the mixing amount of cement. The results of the 7-day compressive strength test are shown in fig. 9 and 10. From fig. 8, 9 and 10, it can be seen that after the modified nano silica is added, the slump is obviously improved compared with that of the unmodified nano silica, so that the construction requirement in engineering is completely met, the early strength of concrete is obviously improved compared with that of a standard sample, and the slump is not met although the strength of the concrete is improved after the silica is directly added, so that the concrete has a certain application value.
According to the polyethylene glycol monomethyl ether acrylate modified nano silica, a large amount of long polymer chains of the water reducing agent are grafted on the silica after chain extension treatment, so that the high molecular weight of the surface can increase the steric hindrance, reduce the aggregation of the silica, and the polymer can play a role of fiber, the compressive strength of the prepared concrete can reach 38.6Mpa under the condition of doping a small amount of nano silica (accounting for 0.25% of the mass of cement), the strength of the prepared concrete is improved by 23.7% compared with the strength of a reference sample of 31.2Mpa, the strength of the concrete doped with 1% of nano silica can reach 41.2Mpa, and the strength of the concrete is improved by 32.1% compared with the strength of the reference sample of 31.22 Mpa. Meanwhile, the defects of poor fluidity, low construction difficulty and the like caused by direct doping of the unmodified nano silicon dioxide are overcome.
The embodiments of the present invention are merely described in terms of preferred embodiments of the present invention, and are not intended to limit the spirit and scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope of the present invention, and the technical content of the present invention as claimed is fully described in the claims.
Claims (8)
1. The preparation method of the high-performance modified nano silicon dioxide is characterized by comprising the following steps of:
step 1, performing functionalization treatment on nano silicon dioxide by adopting a silane coupling agent KH550 to obtain coupled nano silicon dioxide;
step 2, chain extension is carried out on the surface of the nano silicon dioxide coupled in the step 1 by adopting methyl acrylate and ethylenediamine, so as to obtain the nano silicon dioxide modified by the methyl acrylate and ethylenediamine;
step 3, grafting the modified nano silicon dioxide obtained in the step 2 with polyethylene glycol monomethyl ether acrylate to obtain a final product polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide;
the polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide has the chemical formula:
2. the method for preparing high-performance modified nano-silica according to claim 1, wherein the process of step 1 is as follows:
firstly, drying nano silicon dioxide in a vacuum environment at 50-110 ℃ for 10-48h; then dispersing the dried nano silicon dioxide and a silane coupling agent KH550 in toluene, and stirring and reacting for 8-24 hours at 60-120 ℃ after ultrasonic dispersion; after the reaction is finished, the coupled nano silicon dioxide is obtained through centrifugal separation, washing, filtering and drying.
3. The preparation method of the high-performance modified nano silicon dioxide according to claim 2, which is characterized in that the mass ratio of nano silicon dioxide to silane coupling agent KH550 to toluene in the step 1 is as follows: 1 to 5: 2-10: 3 to 40.
4. The method for preparing high-performance modified nano-silica according to claim 1, wherein the process of step 2 is as follows:
adding the coupled nano silicon dioxide and methyl acrylate obtained in the step 1 into solvent methanol, and stirring and reacting for 10-48 hours at 30-80 ℃; then adding 1-10mL of ethylenediamine, stirring and reacting for 10-24 hours; cooling to room temperature after the reaction is finished, and obtaining the methyl acrylate and ethylenediamine modified nano silicon dioxide after centrifugal separation, washing and vacuum drying.
5. The preparation method of the high-performance modified nano silicon dioxide according to claim 4, wherein in the step 2, the mass ratio of the nano silicon dioxide to the methyl acrylate to the ethylenediamine to the solvent methanol is as follows: 2 to 50: 1-20: 1-20: 10 to 100 percent.
6. The method for preparing high-performance modified nano-silica according to claim 1, wherein the process of step 3 is as follows:
adding the modified nano silicon dioxide obtained in the step 2 into dimethyl sulfoxide solvent, then adding polyethylene glycol monomethyl ether acrylate, and stirring at 60-100 ℃ for reaction for 24-72 hours; after the reaction is finished, the polyethylene glycol monomethyl ether acrylate modified nano silicon dioxide serving as a final product is obtained through centrifugal separation, washing and vacuum drying.
7. The preparation method of the high-performance modified nano silicon dioxide according to claim 6, wherein in the step 3, the mass ratio of the modified nano silicon dioxide to polyethylene glycol monomethyl ether acrylate to the solvent dimethyl sulfoxide is as follows: 1-10:5-20: 10 to 100.
8. Use of a high performance modified nano-silica prepared according to any one of claims 1 to 7 for incorporation into cement-based material systems instead of cement.
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